.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
.\"     Fri Apr  2 11:32:09 MET DST 1993
.\"
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.\" This is free documentation; you can redistribute it and/or
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.\" published by the Free Software Foundation; either version 2 of
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.\" Modified Sat Jul 24 17:00:12 1993 by Rik Faith (faith@cs.unc.edu)
.TH NULL 4 2015-07-23 "Linux" "Linux Programmer's Manual"
.SH NAME
null, zero \- data sink
.SH DESCRIPTION
Data written to the
.IR /dev/null
and
.IR /dev/zero
special files is discarded.
.PP
Reads from
.IR /dev/null
always return end of file (i.e.,
.BR read (2)
returns 0), whereas reads from
.IR /dev/zero
always return bytes containing zero (\(aq\e0\(aq characters).
.PP
These devices are typically created by:
.PP
.in +4n
.EX
mknod \-m 666 /dev/null c 1 3
mknod \-m 666 /dev/zero c 1 5
chown root:root /dev/null /dev/zero
.EE
.in
.SH FILES
.I /dev/null
.br
.I /dev/zero
.SH NOTES
If these devices are not writable and readable for all users, many
programs will act strangely.
.PP
Since Linux 2.6.31,
.\" commit 2b83868723d090078ac0e2120e06a1cc94dbaef0
reads from
.IR /dev/zero
are interruptible by signals.
(This change was made to help with bad latencies for large reads from
.IR /dev/zero .)
.SH SEE ALSO
.BR chown (1),
.BR mknod (1),
.BR full (4)
.SH COLOPHON
This page is part of release 5.13 of the Linux
.I man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
\%https://www.kernel.org/doc/man\-pages/.
